Bendroflumethiazide (the generic name for 3-benzyl-3,4-dihydro-7-sulfamoyl-6-trifluoromethyl-1,2,4-benzothiadiazine 1,1-dioxide) is known as a diuretic and antihypertensive agent as disclosed in U.S. Pat. No. 3,265,573. However, bendroflumethiazide has a dissolution problem due to its hydrophobic nature and low solubility. Its in vivo bioavailability is compromised due to its poor dissolution from tablets. Reduction in particle size and selection of a fast dissolving polymorphic form improves its dissolution but not to a desired acceptable level.
When formulated as a tablet, bendroflumethiazide is usually in admixture with gum acacia which serves as a binder, corn starch which serves as a disintegrant, together with a lactose diluent, lubricant and water-soluble dyes.
The prior art bendroflumethiazide tablets are prepared by first dissolving part of the gum acacia binder and water-soluble dyes in water, adding lactose to the resulting solution, drying the mixture, reducing the resulting particles to fine granules, and then mixing such granules with the bendroflumethiazide, cornstarch and remainder of the gum acacia, and compressing the mixture into tablets. Such tablet formulations disintegrate in water after about 9 minutes and have good dissolution properties upon aging. However, tablet formulations which have improved disintegration properties and dissolution properties and are faster and cheaper to manufacture would still be most desirable.